Piezoelectric inertia actuator and method of manufacture

ABSTRACT

A piezoelectric inertia actuator is disclosed herein, which includes an actuator body, a coupling body defining a receiver, a lock body positioned within the receiver, and a piezo body attached to the coupling body. At least one flexible frame configured to support an engaging body may extend from the piezo body. A spring blade configured to apply a preload force to the engaging body via a decoupling preload body may extend from the coupling body. A tension member may be positioned within the lock body and apply a preload force to the piezo body, thereby creating a net compressive stress therein. The piezoelectric inertia actuator may further include a piezo preload body configured to apply a reaction force to the piezo body in order to maintain the compressive stress therein. The preload applied to the piezo body may be substantially decoupled from the preload applied to the engaging body.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 62/837,878—entitled “Piezoelectric Inertia Actuatorand Method of Manufacture” filed on Apr. 24, 2019, the contents of whichare incorporated by reference in its entirety herein.

BACKGROUND

Piezoelectric inertia actuators are used in a variety of motion controldevices. They operate on the principle of stick-slip friction wherein apiezoelectric device expands or contracts based on an alternatingelectrical signal and this alternating change in size is transferred toa carriage or moving stage via a frictional contact with an engagingbody, thereby resulting in a change in position of the carriage. Safeand reliable operation of a piezoelectric inertia actuator requires thatthe piezoelectric device be subject to a compressive stress or preload.Precise control of the position of the carriage requires precise controlof the frictional interface between the carriage and the engaging body.Since friction is usually directly proportional to the normal loadbetween surfaces, some biasing force or preload usually exists betweenthe respective surfaces of the engaging body and the carriage. Precisecontrol of this preload has proven difficult in the past. Additionally,the preload applied to the piezoelectric device may result in unwantedchanges to the preload between the engaging body and the carriage.

As such, there is an ongoing need for an improved piezoelectric inertiaactuator capable of precisely controlling and decoupling the variouspreloads.

SUMMARY

The present application discloses various embodiments of a piezoelectricinertia actuator and methods of manufacture.

In one embodiment, the present application discloses a piezoelectricinertia actuator which may include at least one actuator body, at leastone coupling body defining a receiver, and a lock body configured to bepositioned within the receiver. At least one piezo body may be bonded orotherwise attached to the coupling body. At least one flexible frame mayextend from the piezo body, the flexible frame configured to support atleast one engaging body in communication with the piezo body. At leastone spring blade may extend from the coupling body, the spring bladeconfigured to apply a preload biasing force to the flexible frame andthe engaging body. The piezoelectric inertia actuator may furtherinclude at least one tension member positioned within a tension memberreceiver and configured to selectively apply a preload force to thepiezo body, thereby creating a net compressive stress within the piezobody. The engaging body may be detachably or non-detachably coupled tothe flexible frame. The piezoelectric inertia actuator may furtherinclude at least one piezo preload body in communication with at leastone of the actuator body or the flexible frame, the piezo preload bodybeing configured to apply a reaction force to the piezo body in order tomaintain the net compressive stress within the piezo body. At least onedecoupling preload body may be formed in communication with at least oneof the spring blade, the flexible frame, and the engaging body, thedecoupling preload body configured to adjustably apply a biasing forcegenerated by the spring blade to the engaging body.

In another embodiment, the piezoelectric inertia actuator may include afirst preload zone configured to apply a first preload to at least onepiezo body in a first direction, the first preload zone including atleast one actuator body, at least one lock body, at least one tensionmember positioned within the lock body, at least one coupling body, andat least one piezo preload body. The piezoelectric inertia actuator mayfurther include a second preload zone configured to apply a secondpreload to at least one engaging member in a second direction, thesecond preload zone including at least one spring blade including a flexregion and at least one decoupling preload body, wherein an adjustmentof the first preload does not result in a substantial change of thesecond preload. In one embodiment, the first preload zone and the secondpreload zone are substantially mechanically decoupled. In anotherembodiment, the first preload zone and the second preload zone are notsubstantially mechanically decoupled.

Other features and advantages of the piezoelectric inertia actuator andmethod of manufacture as described herein will become more apparent froma consideration of the following detailed description in conjunctionwith the accompanying exemplary figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of a piezoelectric inertia actuator and method ofmanufacture will be explained in more detail by way of the accompanyingdrawings, wherein:

FIG. 1 shows an elevated perspective view of an embodiment of apiezoelectric inertia actuator;

FIG. 2 shows an elevated perspective view of the embodiment of apiezoelectric inertia actuator shown in FIG. 1;

FIG. 3 shows an elevated perspective view of the embodiment of apiezoelectric inertia actuator shown in FIG. 1;

FIG. 4 shows a cross-sectional view of the embodiment of a piezoelectricinertia actuator shown in FIG. 1; and

FIG. 5 shows a cross-sectional view of the embodiment of a piezoelectricinertia actuator shown in FIG. 1.

DETAILED DESCRIPTION

The present application is directed to various embodiments ofpiezoelectric inertia actuators in the method of manufacture. Theembodiments described herein may be directed to compact motorizeddriving mechanisms, such as piezoelectric inertia drivers, for use inprecision positioning of optical components, optical mounts, kinematicoptical mounts, rotary stages, linear stages, translation mounts,cartridges, and the like. Further, the piezoelectric inertia actuatorsdescribed herein may be manufactured in any desired shape, size, orconfiguration.

FIGS. 1-5 show various views of an embodiment of a piezoelectric inertiaactuator. As shown, the piezoelectric inertia actuator 10 includes atleast one actuator body 12. In one embodiment, the actuator body 12 ismanufactured from stainless steel. Optionally, the actuator body 12 maybe manufactured from any variety of materials including, thoughlimitations, aluminum, brass, copper, titanium, and/or various metals.Optionally, the actuator body 12 may be manufactured from one or morealloys. Exemplary alloys include, without limitations, copper tungsten,sintered powdered metals, nickel steel, nitinol, bronze, and the like.In another embodiment, the actuator body 12 may be manufactured from oneor more polymers, composite materials, and the like. Further, thevarious components forming the piezoelectric inertia actuator may bemanufactured using any variety of machining processes, additivemanufacturing processes, 3D printing, and the like. In the illustratedembodiment, the actuator body 12 includes one or more base regions 60configured to be mounted or secured to a frame or structure configuredto support the piezoelectric inertia actuator 10. Optionally, theactuator body 12 need not include a base region 60.

The piezoelectric inertia actuator 10 may include at least one couplingbody 18 located proximal to, in contact with, or attached to one or morepiezo bodies 20. The piezo body 20 may include piezoelectric crystals,piezoelectric ceramics or any other suitable material that changes outerdimensions relative to the application of an external field or signal,such as an electrical signal—voltage or current. In one embodiment, atleast one adhesive material configured to secure or bond the couplingbody 18 to the piezo body 20 may be applied between the coupling body 18and the piezo body 20. In another embodiment, the coupling body 18 maybe secured to the piezo body 20 with one or more fasteners (not shown).In another embodiment, the coupling body 18 may be secured to the piezobody 20 by a preload force transmitted by the coupling body 18. Thoseskilled in the art will appreciate that any variety of materials,devices or methods may be used to secure the coupling body 18 to thepiezo body 20.

As shown in FIG. 1, one or more extended regions 17 may be formed on thecoupling body 18. In the illustrated embodiment, the coupling body 18has two extended regions 17. Optionally, the coupling body 18 need nothave extended regions 17. In one embodiment, the extended regions 17 arepositioned in contact with opposing sides of at least one lock body 16and are operative to retain or stabilize the coupling body 18 and thepiezo body 20 laterally (i.e. in the Z-direction) with respect to thelock body 16. In another embodiment, the extended regions 17 may be usedto dampen lateral vibrations of the lock body 16, the coupling body 18and or the piezo body. Optionally, the extended regions 17 may not be inphysical contact with the lock body 16. One or more receivers 14 may beformed in the coupling body 18 between the two extended regions 17. Inone embodiment, the receiver 14 is configured to receive the lock bodyor member 16 therein. Like the actuator body 12, the lock body 16 may bemanufactured from any variety of materials described above.

As shown in FIGS. 3-5, the lock body 16 may include one or morefasteners or tension members 44 positioned in one or more tension memberreceivers 46 formed in the lock body 16. In one embodiment, the tensionmember 44 may be used to secure the coupling body 18 to the piezo body20. In another embodiment, the tension member may apply a preload orcompression stress to the piezo body 20 in order to secure it within thepiezoelectric inertia actuator 10, or to ensure proper and safeoperation of the piezoelectric inertia actuator 10. In one embodiment,the user may vary the preload applied to at least a portion of the piezobody 20 by tightening or loosening the tension member 44 positionedwithin the tension member receiver 46. Optionally, the tension member 44may traverse through the actuator body 12, the lock body 16, thereceiver 14, and the coupling body 18 and may directly engage the piezobody 20, thereby securely coupling the piezo body 20 to the actuatorbody 12. As such, the actuator body 12, the lock body 16, receiver 14,and coupling body 18 may be configured to provide a rigid structure. Thetension member 44 may be provided as a threaded member, a micrometeradjuster or linear actuator. Those skilled in the art will appreciatethat any variety of adjusting devices may be used as the tension member44.

As shown in FIGS. 1 and 2, one or more conduits 30 may be coupled to thepiezo body 20 and configured to selectively provide voltage and/orcurrent to the piezo body 20. In the illustrated embodiment, theconduits 30 are coupled to the piezo body 20 via one or more conduitconnectors 32. As such, the piezo body 20 may be in communication withat least one source of voltage and/or current via the conduits 30. Inone embodiment, the conduit connectors 32 are solder bumps applied toopposite sides of the piezo body 20 configured to attach the conduits 30to the piezo body 20. Optionally, the piezoelectric inertia actuator 10shown in FIGS. 1-4 need not include conduit connectors 32.

Referring again to FIGS. 4 and 5, at least one flexible frame 22 may becoupled to and extend from the piezo body 20. The piezo body 20 may besecured to the flexible frame 22 with an adhesive material, fastener, orpreload force such as those described above with respect to securing thepiezo body 20 to the coupling body 18. As shown, the flexible frame 22may include at least one flex region 24 formed thereon. Further, theflexible frame 22 may further include at least one engaging body 26coupled to at least a portion of the flexible frame 22 and configured tocontact and engage at least one carriage 56 at at least one contactpoint 28. In one embodiment, the flexible frame 22 and the variouscomponents thereof may be manufactured from any variety of materials.For example, in one embodiment the flexible frame 22 is manufacturedfrom stainless steel. In another embodiment, the flexible frame 22 ismanufactured from aluminum. Optionally, the flexible frame 22 may bemanufactured from various metals including, without limitation, steel,copper, titanium, and/or various metals. Optionally, the flexible frame22 may be manufactured from one or more alloys. Exemplary alloysinclude, without limitations, copper tungsten, sintered powdered metals,nickel steel, nitinol, brass, bronze, and the like. In anotherembodiment, the flexible frame 22 may be manufactured from one or morepolymers, composite materials, and the like. Further, the flexible frame22, flex region 24, and engaging body 26 may be manufactured from asingle material. Optionally, the flexible frame 22, flex region 24, andengaging body 26 may be manufactured from different materials. In oneembodiment, the engaging body 26 is detachably coupled to the flexibleframe 22. In an alternate embodiment, the engaging body 26 may benon-detachably coupled to the flexible frame 22.

In one embodiment, the flexible frame 22 is configured to provide arigid structure in the X-direction (see FIG. 5.), and provide a flexiblestructure in the Y-direction. The rigid structure in the X-direction isoperative to transmit the alternating expansion and contraction of thepiezo body 20 to the engaging body 26 in order to move the carriage 56in the X-direction. The flexible structure in the Y-direction isconfigured to transmit a preload force to the engaging body 26 to allowfor control of friction at the contact point 28 between the engagingbody 26 and the carriage 56. In another embodiment, the flexible frame22 may be configured to provide a flexible structure in the X-direction,and a rigid structure in the Y-direction. Those skilled in the art willappreciate that the flexible frame 22 may be configured to provide anylevel of stiffness or flexibility in either the X-direction or theY-direction.

In the illustrated embodiment, the engaging body 26 has a radius formedthereon, with a single contact point 28. Optionally, the engaging body26 may have any number of contact points 28. Alternatively, the engagingbody 26 may have any geometry formed at the contact point. Those skilledin the art will appreciate that the engaging body 26 may be formed inany variety of shapes, geometries, sizes, surface finishes, andconfigurations. As described above, the engaging body 26 may be formedfrom a different material than the actuator body 12 and the flexibleframe 24. As such, the properties of the material used in the engagingbody 26 may be chosen to be compatible with the material of the carriage56 (see FIG. 5). For example, if the material of the carriage 56 at thecontact point 28 is a stainless steel, then the optimum material for theengaging body 26 may be silicon carbide with a relatively rough surfacefinish. Also, since the engaging body 26 may be detachably coupled tothe flexible frame 24, the engaging body may be able to be replacedwithout replacement of the other components of the piezoelectric inertiaactuator 10.

As shown in FIGS. 1-4, the actuator body 12 may include at least onerecess 34 formed therein. In the illustrated embodiment, the recess 34is formed proximate to the flex region 24 formed on the flexible frame22 and/or the engaging body 26. Those skilled in the art will appreciatethat the recess 34 may be formed anywhere on the actuator body 12 or thepiezoelectric inertia actuator 10. Further, the piezoelectric inertiaactuator 10 need not include a recess 34.

As shown in FIGS. 4 and 5, at least one spring blade, biasing blade orflexible member 40 may extend from the actuator body 12 and traverse atleast a portion of the recess 34. In the illustrated embodiment, thespring blade 40 is used to apply or transmit a preload force 39 to theflexible frame 22 and/or the engaging body 26. As shown, the springblade 40 may include at least one flex region 50 formed thereon, therebypermitting a user to vary the biasing force 39 applied by the springblade 40. Optionally, the spring blade 40 need not include a flex region50. At least one relief 42 may be formed between the base region 60 andthe spring blade 40, the relief 42 configured to give the spring blade40 sufficient flexibility to precisely control the preload of theengaging body 26 against the carriage 56. The spring blade 40 may alsoinclude at least one extended region 48 configured to be contacted by atleast one adjusting member or device 53 configured to provide a preloadforce 52 to the spring body 40. Optionally, the spring blade 40 may notinclude an extended region 48. In one embodiment, the preload force 52may be variable. In another embodiment, the preload force 52 may befixed or pre-set during manufacture. In another embodiment, the preloadforce 52 may be actively adjustable during operation of thepiezoelectric inertia actuator 10. In one embodiment, the adjustingdevice 53 is a threaded member such as a set screw. Optionally, theadjusting device 53 may be a micrometer adjuster or linear actuator.Those skilled in the art will appreciate that any variety of devices maybe used as the adjusting device 53. At least one recess 54 may be formedin the actuator body 12 between the spring blade 40, the flexible frame22 and engaging body 26, the recess 54 configured to allow deflection ofthe spring blade 40 and the extended region 48.

Referring again to FIGS. 1-5, the piezoelectric inertia actuator 10 mayinclude at least one decoupling preload body 38. In the illustratedembodiment, the decoupling preload body 38 is formed integral to thespring blade 40 and extends from the spring blade 40 to the portion ofthe flexible frame 22 that supports or is coupled to the engaging body26. Optionally, the decoupling preload body 38 need not be integral tothe spring blade 40. In one embodiment, the biasing force 52 is exertedon the extended region 48 of the spring blade 40, thereby resulting in apreload force 39 being exerted on the flexible frame 22 and the engagingbody 26 by the decoupling preload body 38. In one embodiment, thepreload biasing force 39 applied by the decoupling preload body 38 tothe engaging body 26 may be predetermined or preset. In an alternateembodiment, the preload biasing force 39 applied by the decouplingpreload body 38 may be adjustable by the user. Because the preload canbe maintained by the elastic deflection of the spring blade 40, thepreload on the engaging body 26 may be less affected by geometricsurface defects (wear, flat points, bumps, etc.) in the carriage 56. Assuch, unlike prior art piezoelectric inertia actuators, the preloadbiasing force 39 applied to the engaging body 26 may be adjusted byvarying the position of the spring blade 40.

At least one piezo preload body 36 may be coupled to at least one of theactuator body 12, the flexible frame 22 and the spring blade 40. In oneembodiment, the piezo preload body 36 may be configured to apply apre-determined biasing force to the flexible frame 22 and/or the springblade 40. In another embodiment, the piezo preload body 36 may beconfigured to deflect elastically, thereby maintaining the preloadstress in the piezo body 20 that is exerted by the tension member 44,resulting in a reaction force 37 exerted on the piezo body 20 by thepiezo preload body 36. Further, a user may vary the preload on the piezobody 20 by actuating both the tension member 44 positioned on theactuator body 12 and varying the biasing force 39 applied by the piezopreload body 36. In one embodiment, the piezo preload body 36 may beintegral to the actuator body 12. As such, the piezo preload body 36 maybe manufactured from the same material as at least a portion of theactuator body 12. In another embodiment, the piezo preload body 36 maybe manufactured from a different material than the actuator body 12.

FIG. 5 shows a cross-sectional view of the piezoelectric inertiaactuator 10. As described above, piezoelectric devices (such as thepiezo body 20) require a compressive preload to ensure safe and reliablefunction. Also, the friction between the engaging body 26 and thecarriage 56 at the contact point 28 should be controlled in order toallow predictable and precise control of the position of the carriage56. Ideally, changes in the preload of the piezo body 20 should notresult in a change in the preload at the contact point 28.

As shown in FIG. 5, in the illustrated embodiment, a first preload zone70 and a second preload zone 80 are defined in the piezoelectric inertiaactuator 10. Within the first preload zone 70, a preload force 45 on thepiezo body 20 in the X-direction may be applied and adjusted byactuation of the tension member 44 within the lock body 16. Because, inthe illustrated embodiment, the lock body 16 and the piezo preload body36 are integral to and extend from the actuator body 12, the preloadforce 45 results in a reaction force 37 in the opposite X-direction dueto the deflection of the piezo preload body 36 relative to the lock body16, thereby maintaining a compressive stress in the piezo body 20. Inone embodiment, the deflection of the piezo preload body 36 is elastic.In another embodiment, the deflection of the piezo preload body 36results in plastic deformation of the piezo preload body 36. Because thepiezo preload body 36 branches from the actuator body 12 at a point inthe X-direction before the spring blade 40 extends from the actuatorbody 12, a deflection in the piezo preload body 36 will result in aminimal deflection of the spring blade. As such, the preload on thepiezo body 20 in the X-direction may be substantially decoupled from thepreload on the contact point 28 in the Y-direction.

As shown in FIGS. 4 and 5, within the second preload zone 80, a preloadforce 52 exerted on the extended portion 48 of the spring blade 40 bythe adjusting device 53, results in a preload force 39 in theY-direction being transmitted to the engaging body 26, thereby providinga preload between the engaging body 26 and the carriage 56 at thecontact point 28. Because, as described above, the spring blade 40(including the flex region 50) and the flexible frame 22 are relativelyflexible in the Y-direction, a change in the amount of preload at thecontact point 28 may result in only a very small change in the preloadon the piezo body 20. As such, the preload on the contact point 28 inthe Y-direction may be substantially decoupled from the preload on thepiezo body 20 in the X-direction. Those skilled in the art willappreciate that the preloads in the first preload zone and the secondpreload zone may not be completely decoupled from the other. The designgeometry of the piezoelectric inertia actuator 10 may be tailored sothat the preloads in the first preload zone and the second preload zonedo affect each other in a way defined by design choice. Also thoseskilled in the art will appreciate that there may be any number ofpreload zones defined in the piezoelectric inertia actuator 10.

The present application describes various embodiments of piezoelectricinertia actuators. While particular embodiments have been illustratedand described herein, it will be apparent that modifications to thedesign may be made without departing from the spirit and scope of theembodiments of the invention. As such, it is appreciated by personsskilled in the art that the present invention is not limited by what hasbeen particularly shown and described above herein. Rather, the scope ofthe present invention includes both combinations and sub-combinations ofvarious features described hereinabove as well as variations andmodifications thereto which would occur to a person of skill in the artupon reading the above description and which are not in the prior art.

What is claimed:
 1. A piezoelectric inertia actuator, comprising: at least one actuator body (12); at least one coupling body (18) defining a receiver (14); at least one lock body (16) configured to be positioned within the receiver (14) formed in the coupling body (18); at least one piezo body (20) coupled to the coupling body (18); at least one flexible frame (22) coupled to and extending from the piezo body (20); at least one engaging body (26) in communication with the piezo body (20) via the flexible frame (22); and at least one spring blade (40) extending from the actuator body (12), the spring blade (40) configured to selectively apply a preload biasing force (39) to at least one of the flexible frame (22) and the engaging body (26).
 2. The piezoelectric inertia actuator of claim 1, wherein the actuator body (12) and lock body (16) form a monolithic structure.
 3. The piezoelectric inertia actuator of claim 1, further comprising at least one tension member receiver (46) formed in the lock body (16).
 4. The piezoelectric inertia actuator of claim 3, further comprising at least one tension member (44) positioned within the tension member receiver (46) and configured to selectively engage the coupling body (18) and piezo body (20) to apply a preload force (45) to the piezo body (20), the preload force (45) configured to result in a net compressive stress within the piezo body (20).
 5. The piezoelectric inertia actuator of claim 1, wherein the actuator body (12), lock body (16), tension member (44), coupling body (18) and piezo body (20) form a rigid structure.
 6. The piezoelectric inertia actuator of claim 1, further comprising at least one conduit (30) coupled to the piezo body (20) and in communication with at least one source of voltage or current.
 7. The piezoelectric inertia actuator of claim 1, wherein the flexible frame (22) further comprises at least one flex region (24).
 8. The piezoelectric inertia actuator of claim 1, wherein the engaging body (26) is detachably coupled to the flexible frame (22).
 9. The piezoelectric inertia actuator of claim 1, wherein the engaging body (26) is non-detachably coupled to the flexible frame (22).
 10. The piezoelectric inertia actuator of claim 4, further comprising at least one piezo preload body (36) in communication with at least one of the actuator body (12) or the flexible frame (22), the piezo preload body (36) configured to apply a reaction force (37) to the piezo body (20) to maintain the net compressive stress within the piezo body (20).
 11. The piezoelectric inertia actuator of claim 1, further comprising at least one decoupling preload body (38) in communication with at least one of the spring blade (40), the flexible frame (22) and the engaging body (26), the decoupling preload body (38) configured to adjustably apply a biasing force (39) generated by the spring blade (40) to the engaging body (26).
 12. The piezoelectric inertia actuator of claim 11, wherein a change in a preload force (45) to the piezo body (20) does not result in a substantial change in the biasing force (39) applied to the engaging body (26) by the decoupling preload body (38).
 13. A piezoelectric inertia actuator, comprising: an actuator body (12); at least one lock body (16) formed on the actuator body (12); at least one tension member receiver (46) formed in the lock body (16) and configured to accept at least one tension member (44), the tension member (44) configured to apply a preload force (45) to at least one coupling body (18); at least one piezo body (20) coupled to the coupling body (18); at least one flexible frame (22) coupled to and extending from the piezo body (20); at least one engaging body (26) in communication with the piezo body (20) via the flexible frame (22); and at least one spring blade (40) extending from the actuator body (12), the spring blade (40) configured to selectively apply a preload biasing force (39) to at least one of the flexible frame (22) and the engaging body (26) via at least one decoupling preload body (38).
 14. The piezoelectric inertia actuator of claim 13, further comprising at least one piezo preload body (36) formed on the actuator body (12) and in communication with the flexible frame (22) and the piezo body (20).
 15. The piezoelectric inertia actuator of claim 14, wherein the piezo preload body (36) is configured to apply a reaction force (37) to the piezo body (20).
 16. The piezoelectric inertia actuator of claim 15, further comprising: a first preload zone (70), configured to apply a first preload to the piezo body (20) in a first direction, the first preload zone (70) including the actuator body (12), the lock body (16), the tension member (44), the coupling body (18), the flexible frame (22) and the piezo preload body (36); a second preload zone (80), configured to apply a second preload to the engaging member (26) in a second direction, the second preload zone including the spring blade (40), the flex region (50) and the decoupling preload body (38); and wherein an adjustment of the first preload does not result in a substantial change of the second preload.
 17. The piezoelectric inertia actuator of claim 16, wherein the first preload zone (70) and the second preload zone (80) are substantially mechanically decoupled.
 18. The piezoelectric inertia actuator of claim 16, wherein the first preload zone (70) and the second preload zone (80) are not substantially mechanically decoupled. 